1. School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom, Dipartimento di Chimica Organica “U. Schiff”, Università di Firenze, Via della Lastruccia, 13, I-50019, Sesto Fiorentino, Italy, and Pfizer Global Research & Development, Ramsgate Road, Sandwich, Kent, CT13 9NJ, United Kingdom